Nitrogen

CAN YOU SEE OR SMELL THE INVISIBLE KILLER?

No!

how are you sure it is safe to enter..
What are your precautionary measures before entry..
Do you carry a portable gas detector that beeps if oxygen falls below 19%..
Do you have a standby attendant..
Do you know that you can be overcome by N₂ by just looking into the manhole without wearing breathing apparatus..
Never put your head into open connections of storage tanks, columns, flange connections etc.

The atmosphere we live in, the air we breathe every day consists of 78% Nitrogen, 21% Oxygen and 1% traces of other gases. But only oxygen is vital and essential to human beings for respiration/survival. Without sufficient oxygen, i.e. if oxygen level falls below 16%, we will die of asphyxiation.

Oxygen (%vol)	Effects and Symptoms
23.5	Maximum "Safe Level" (23% is often the High level alarm of most O2 detectors)
21	Typical O2 concentration in air
19.5	Minimum "Safe Level" (19% is often the Low level alarm of most O2 detectors)
15-19	First sign of hypoxia. Decreased ability to work strenuously. May induce early symptoms in persons with coronary, pulmonary or circulatory problems
12-14	Respiration increases with exertion, pulse up, impaired muscular coordination, perception and judgment
10-12	Respiration further increases in rate and depth, poor judgment, lips blue
8-10	Mental failure, fainting, unconsciousness, ashen face, blueness of lips, nausea, vomiting, inability to move freely
6-8	6 minutes - 50% probability of death, 8 minutes - 100% probability of death
4-6	Coma in 40 seconds, convulsions, respiration ceases, death

What is an Asphyxiant..

A chemical (gas or vapour) that can cause death or unconsciousness by suffocation.
Simple aphyxiants such as nitrogen, displace oxygen in air.
They become especially dangerous in confined or enclosed spaces.
Chemical asphyxiants, such as carbon monoxide and hydrogen sulfide, interfere with the body's ability to absorb or transport oxygen to the tissues.

Hazards of Nitrogen Asphyxiation